Preparation of Na–Al–O films by laser chemical vapor deposition

Abstract

h i g h l i g h t s NaAlO 2 and NaAl 6 O 9.5 films were fabricated by laser chemical vapor deposition.(110)-oriented g-NaAlO 2 films having roof-like faceted morphology were grown.Pyramidally and polygonally faceted NaAl 6 O 9.5 films formed with (041)-orientation formed.High deposition rates for single-phase g-NaAlO 2 films were over 100 mm h À1 . a b s t r a c tNaeAleO films were prepared on AlN substrates by laser chemical vapor deposition at deposition temperatures (T dep ) of 940e1250 K, molar ratios of Na to Al precursors (R Na/Al ) of 0.2e3 and total pressures (P tot ) of 100e800 Pa. Single-phase NaAlO 2 films were deposited at T dep ¼ 940e1080 K, R Na/ Al ¼ 1.5e3 and P tot ¼ 100e800 Pa. The (110)-oriented g-NaAlO 2 films showed roof-like grains, whereas the (200)-oriented g-NaAlO 2 films had finely faceted grains. Single-phase NaAl 6 O 9.5 formed at T dep ¼ 1018e1125 K, R Na/Al ¼ 0.4e3.0 and P tot ¼ 100e600 Pa NaAl 6 O 9.5 films had (041) orientation with pyramidally and polygonally faceted grains. At T dep > 1100 K, a-Al 2 O 3 films, consisting of polygonally faceted grains, formed. The highest deposition rate was 131 mm h À1 for the g-NaAlO 2 film at T dep ¼ 986 K, R Na/Al ¼ 3.0 and P tot ¼ 200 Pa.